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Stress rapidly suppresses in vivo LH pulses and increases activation of RFRP-3 neurons in male mice
Restraint stress is a psychosocial stressor that suppresses reproductive status, including LH pulsatile secretion, but the neuroendocrine mechanisms underlying this inhibition remains unclear. Reproductive neural populations upstream of gonadotropin-releasing hormone (GnRH) neurons, such as kisspeptin, neurokinin B and RFRP-3 (GnIH) neurons, are possible targets for psychosocial stress to inhibit LH pulses, but this has not been well examined, especially in mice in which prior technical limitations prevented assessment of in vivo LH pulse secretion dynamics. Here, we examined whether one-time acute restraint stress alters in vivo LH pulsatility and reproductive neural populations in male mice, and what the time-course is for such alterations. We found that endogenous LH pulses in castrated male mice are robustly and rapidly suppressed by one-time, acute restraint stress, with suppression observed as quickly as 12–18 min. This rapid LH suppression parallels with increased in vivo corticosterone levels within 15 min of restraint stress. Although Kiss1, Tac2 and Rfrp gene expression in the hypothalamus did not significantly change after 90 or 180 min restraint stress, arcuate Kiss1 neural activation was significantly decreased after 180 min. Interestingly, hypothalamic Rfrp neuronal activation was strongly increased at early times after restraint stress initiation, but was attenuated to levels lower than controls by 180 min of restraint stress. Thus, the male neuroendocrine reproductive axis is quite sensitive to short-term stress exposure, with significantly decreased pulsatile LH secretion and increased hypothalamic Rfrp neuronal activation occurring rapidly, within minutes, and decreased Kiss1 neuronal activation also occurring after longer stress durations
Separating the effects of changes in land cover and climate: a hydro-meteorological analysis of the past 60 yr in Saxony, Germany
Understanding and quantifying the impact of changes in climate and land
use/land cover on water availability is a prerequisite to adapt water
management; yet, it can be difficult to separate the effects of these
different impacts. In this paper we illustrate a separation and attribution
method based on a Budyko framework. We assume that evapotranspiration (<i>E</i><sub>T</sub>) is limited
by the climatic forcing of precipitation (<i>P</i>) and evaporative demand (<i>E</i><sub>0</sub>),
but modified by land-surface properties. Impacts of changes in climate
(i.e., <i>E</i><sub>0</sub>/<i>P</i>) or land-surface changes on <i>E</i><sub>T</sub> alter the two
dimensionless measures describing relative water (<i>E</i><sub>T</sub>/<i>P</i>) and energy
partitioning (<i>E</i><sub>T</sub>/<i>E</i><sub>0</sub>), which allows us to separate and quantify
these impacts. We use the separation method to quantify the role of
environmental factors on <i>E</i><sub>T</sub> using 68 small to medium range river
basins covering the greatest part of the German Federal State of Saxony
within the period of 1950–2009. The region can be considered as a typical
central European landscape with considerable anthropogenic impacts. In the
long term, most basins are found to follow the Budyko curve which we
interpret as a result of the strong interactions of climate, soils and
vegetation. However, two groups of basins deviate. Agriculturally dominated
basins at lower altitudes exceed the Budyko curve while a set of high
altitude, forested basins fall well below. When visualizing the decadal
dynamics on the relative partitioning of water and energy the impacts of
climatic and land-surface changes become apparent. After 1960 higher forested
basins experienced large land-surface changes which show that the air
pollution driven tree damages have led to a decline of annual <i>E</i><sub>T</sub>
on the order of 38%. In contrast, lower, agricultural dominated areas show
no significant changes during that time. However, since the 1990s effective
mitigation measures on industrial pollution have been established and the
apparent brightening and regrowth has resulted in a significant increase of
<i>E</i><sub>T</sub> across most basins. In conclusion, data on both, the water and
the energy balance is necessary to understand how long-term climate and land
cover control evapotranspiration and thus water availability. Further, the
detected land-surface change impacts are consistent in space and time with
independent forest damage data and thus confirm the validity of the
separation approach
Accurate determination of the free-free Gaunt factor. II - relativistic Gaunt factors
When modelling an ionised plasma, all spectral synthesis codes need the
thermally averaged free-free Gaunt factor defined over a very wide range of
parameter space in order to produce an accurate prediction for the spectrum.
Until now no data set exists that would meet these needs completely. We have
therefore produced a table of relativistic Gaunt factors over a much wider
range of parameter space than has ever been produced before. We present tables
of the thermally averaged Gaunt factor covering the range log10(gamma^2) = -6
to 10 and log10(u) = -16 to 13 for all atomic numbers Z = 1 through 36. The
data were calculated using the relativistic Bethe-Heitler-Elwert (BHE)
approximation and were subsequently merged with accurate non-relativistic
results in those parts of the parameter space where the BHE approximation is
not valid. These data will be incorporated in the next major release of the
spectral synthesis code Cloudy. We also produced tables of the frequency
integrated Gaunt factor covering the parameter space log10(gamma^2) = -6 to 10
for all values of Z between 1 and 36. All the data presented in this paper are
available online.Comment: 8 pages, 8 figures, 2 table
Suzaku Reveals Helium-burning Products in the X-ray Emitting Planetary Nebula BD+303639
BD+303639, the brightest planetary nebula at X-ray energies, was observed
with Suzaku, an X-ray observatory launched on 2005 July 10. Using the X-ray
Imaging Spectrometer, the K-lines from C VI, O VII, and O VIII were resolved
for the first time, and C/O, N/O, and Ne/O abundance ratios determined. The C/O
and Ne/O abundance ratios exceed the solar value by a factor of at least 30 and
5, respectively. These results indicate that the X-rays are emitted mainly by
helium shell-burning products.Comment: 12 pages, 4 figures, accepted for publication in The Astrophysical
Journal Letter
Ischemic preconditioning attenuates portal venous plasma concentrations of purines following warm liver ischemia in man
Background/Aims: Degradation of adenine nucleotides to adenosine has been suggested to play a critical role in ischemic preconditioning (IPC). Thus, we questioned in patients undergoing partial hepatectomy whether (i) IPC will increase plasma purine catabolites and whether (ii) formation of purines in response to vascular clamping (Pringle maneuver) can be attenuated by prior IPC. Methods: 75 patients were randomly assigned to three groups: group I underwent hepatectomy without vascular clamping; group II was subjected to the Pringle maneuver during resection, and group III was preconditioned (10 min ischemia and 10 min reperfusion) prior to the Pringle maneuver for resection. Central, portal venous and arterial plasma concentrations of adenosine, inosine, hypoxanthine and xanthine were determined by high-performance liquid chromatography. Results: Duration of the Pringle maneuver did not differ between patients with or without IPC. Surgery without vascular clamping had only a minor effect on plasma purine transiently increased. After the Pringle maneuver alone, purine plasma concentrations were most increased. This strong rise in plasma purines caused by the Pringle maneuver, however, was significantly attenuated by IPC. When portal venous minus arterial concentration difference was calculated for inosine or hypoxanthine, the respective differences became positive in patients subjected to the Pringle maneuver and were completely prevented by preconditioning. Conclusion: These data demonstrate that (i) IPC increases formation of adenosine, and that (ii) the unwanted degradation of adenine nucleotides to purines caused by the Pringle maneuver can be attenuated by IPC. Because IPC also induces a decrease of portal venous minus arterial purine plasma concentration differences, IPC might possibly decrease disturbances in the energy metabolism in the intestine as well. Copyright (C) 2005 S. Karger AG, Basel
Spin-orbit coupling and phase-coherence in InAs nanowires
We investigated the magnetotransport of InAs nanowires grown by selective
area metal-organic vapor phase epitaxy. In the temperature range between 0.5
and 30 K reproducible fluctuations in the conductance upon variation of the
magnetic field or the back-gate voltage are observed, which are attributed to
electron interference effects in small disordered conductors. From the
correlation field of the magnetoconductance fluctuations the phase-coherence
length l_phi is determined. At the lowest temperatures l_phi is found to be at
least 300 nm, while for temperatures exceeding 2 K a monotonous decrease of
l_phi with temperature is observed. A direct observation of the weak
antilocalization effect indicating the presence of spin-orbit coupling is
masked by the strong magnetoconductance fluctuations. However, by averaging the
magnetoconductance over a range of gate voltages a clear peak in the
magnetoconductance due to the weak antilocalization effect was resolved. By
comparison of the experimental data to simulations based on a recursive
two-dimensional Green's function approach a spin-orbit scattering length of
approximately 70 nm was extracted, indicating the presence of strong spin-orbit
coupling.Comment: 8 pages, 7 figure
Accurate determination of the free-free Gaunt factor; I - non-relativistic Gaunt factors
Modern spectral synthesis codes need the thermally averaged free-free Gaunt
factor defined over a very wide range of parameter space in order to produce an
accurate prediction for the spectrum emitted by an ionized plasma. Until now no
set of data exists that would meet this need in a fully satisfactory way. We
have therefore undertaken to produce a table of very accurate non-relativistic
Gaunt factors over a much wider range of parameters than has ever been produced
before. We first produced a table of non-averaged Gaunt factors, covering the
parameter space log10(epsilon_i) = -20 to +10 and log10(w) = -30 to +25. We
then continued to produce a table of thermally averaged Gaunt factors covering
the parameter space log10(gamma^2) = -6 to +10 and log10(u) = -16 to +13.
Finally we produced a table of the frequency integrated Gaunt factor covering
the parameter space log10(gamma^2) = -6 to +10. All the data presented in this
paper are available online.Comment: 10 pages, 5 tables, 3 figures. Fixed typo in Eq. 1
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